"Crowding" in normal and amblyopic vision assessed with Gaussian and Gabor C's
"Crowding" in normal and amblyopic vision assessed with Gaussian and Gabor C's
复制标题
DOI：
10.1016/j.visres.2004.09.035
复制
发表时间：
2005-03-01
期刊：
影响因子：
1.8
通讯作者：
Klein, SA
中科院分区：
文献类型：
--
作者：
Hariharan, S;Levi, DM;Klein, SA
本研究的目的是使用“C”样模式研究正常中央凹和周边以及弱视中央视野的拥挤程度和特异性。在第一个实验中，我们使用四种替代强制选择（上、下、左、右）方法测量了由高斯斑块组成的 C 模式在一系列目标尺寸上的拥挤程度。我们发现中心凹拥挤的程度与目标尺寸成正比。相比之下，在弱视的正常外围和中心视野中，拥挤会延伸到很大的空间距离，并且与大小无关。同极性和相反极性的斑块都会对我们的刺激造成拥挤。为了测试弱视的扩展拥挤是否是由于分析空间尺度的变化造成的，我们在间隙定位任务 (2-AFC) 中测量了带限 C 模式（由 Gabor 斑块组成）的拥挤。在带限刺激和不涉及判断间隙方向的任务下，弱视眼在比正常观察者更长的距离上表现出拥挤。我们还通过改变侧面的方向来测试拥挤的方向特异性。在正常的中央凹中，拥挤是特定方向的；而在弱视中则不然。虽然正常中央凹中的拥挤可以通过简单的图案掩蔽来解释，但正常周边和弱视眼中看到的拥挤却不能。相反，我们认为弱视和周边视觉的拥挤是特征检测阶段之后的阶段中扩展池化的结果。 (C) 2004 Elsevier Ltd. 保留所有权利。
The purpose of this study was to investigate the extent and specificity of crowding in the normal fovea and periphery, and the central field of amblyopes, using "C"-like patterns. In the first experiment we measured the extent of crowding for C-patterns comprised of Gaussian patches, over a range of target sizes using a four-alternative forced-choice (up, down, left, right) method. We found that the extent of foveal crowding is proportional to target size. In contrast, in normal periphery and in the central field of amblyopes, crowding extends over large spatial distances and is not size dependent. Crowding for our stimuli occurred with both same-polarity and opposite polarity patches. To test whether the extended crowding in amblyopia resulted from a shift in the spatial scale of analysis, we measured crowding with band-limited C-patterns (comprised of Gabor patches) in a gap localization task (2-AFC). With band-limited stimuli, and a task that does not involve judging the orientation of the gap, the amblyopic eyes showed crowding over a longer distance than that of normal observers. We also tested the orientation specificity of crowding by varying the orientation of the flanks. In normal fovea, crowding is orientation specific: in amblyopia it is not. While crowding, in normal fovea can be explained by simple pattern masking, crowding seen in normal periphery and amblyopes cannot. Instead we suggest that crowding in amblyopic and peripheral vision is a result of extended pooling at a stage following the stage of feature detection. (C) 2004 Elsevier Ltd. All rights reserved.